Role of the amygdala evaluation

• The amygdala’s role in aggressive behaviour is well established. Many studies have found that increase amygdala activity is involved in aggression.
• Gospic (2011)

  Used the ultimatum game,a lab based method of measuring aggressive behaviour. It involves two players - a Proposer and a Responder, and a sum of money.

  The proposer offers to split the money in a ‘fair’ or ‘unfair’ way. If accepted it is split.  If rejected, the responder is considered aggressive.
• Gospic (2011)

  The researchers found that when responders rejected unfair offers, amygdala activity (FMRI measured) was heightened and quicker.

  This is strong evidence between reactive (hot blooded) aggression and increased amygdala activity.
• It is unlikely that the amygdala works in isolation to create violent behaviour
• Derntl et al (2009)


  Used MRI scans to investigate the effect of testosterone on amygdala activity in healthy male participants
• Increased levels of testosterone improved the amygdala's ability to process threat-related stimuli (fearful and angry facial expressions)
• Derntl et al (2009): '"when confronted with human facial expressions, testosterone prepares females and males for further behavioural activation by enforcing more automatic and autonomic processes leading to attentional shifts and decrease of subconscious fear thereby facilitating approach behaviour"'
• Testosterone levels


  More common in males
• Higher testosterone levels in males


  Could explain why violent crime is much more common amongst males
• One potential issue with this theory is that of cause and effect.

   Is it that the defects in amygdala function occur first, and this causes the criminal behaviour? 

  Or is it that the criminal behaviour causes changes to the amygdala?

   One way in which to answer this question is to look at longitudinal research
• Pardini (2014)

  Selected 503 males who had been part of an earlier study in th 80’s when they were 6/7 years old.

  27 years later the researchers identified a subgroup of 56 men who had shown aggressive behaviour since childhood, including involvement in serious criminal violence (rape, robbery, gang violence) fMRI scans found lower levels of amygdala volumes.

  THis is powerful support for amygdala and aggression and has great predictive validity.
• Changes in the amygdala

  Cause aggressive and/or criminal behaviour
• Possible causes of changes to the amygdala

  • Upbringing
  • Other environmental factor
  • Problems in the pre-natal environment
  • Genes
• Genes as a cause

  Criminals inherit a particular gene or set of genes which cause the amygdala dysfunction, and this leads to the criminal behaviour
• The role of the amygdala remains an incomplete theory on its own
• The amygdala also remains an incomplete theory as it cannot account for all criminal behaviour. Not all criminals have dysfunction in their amygdala, and not all people with amygdala dysfunction show criminal or violent behaviour (for example the case study of SM). 
• The theory could be argued to be reductionist
• This theory ignores the role of society and culture
• All criminals are assessed equally regardless of socioeconomic background or education
• Is it necessarily appropriate to say that the causes of crime are the same for a poorly educated working class person with a limited education as a successful, well-educated businessman?

  No
• The real causes of crime are varied, and complicated
• It is probably better to take an interactionist approach, seeing genes, brain structures, society, upbringing and personality all interacting to cause criminal behaviour
• What is considered to be a crime depends upon your culture, and the time period in which you live. 

  Cultural views on what is criminal can change within a decade, however it would be hard to argue that the function of the amygdala could change as quickly. 
• A lot of the research has focused solely on men, and theories have either ignored women, or applied the same theories to them as to men. 

  There has been little attempt to investigate criminality in women, and it may not be appropriate to assume that the reasons women become criminals are the same as men. 

  This theory of crime therefore could be falling for a beta bias.
• In particular, the study by Derntl et al (2009) above suggests that amygdala function can be affected by testosterone levels.

  Therefore, it may not be appropriate to assume that we can generalise studies on amygdala function from males to females due to hormonal differences.

  It may be that oestrogen has a different effect on the amygdala in females than testosterone does in males.
• If we blame the amygdala for criminal behaviour, then what happens to people who are found to have dysfunctional amygdalae?

  On the one hand, identifying the dysfunction may allow psychologists to stage interventions early in life to alter a child’s behaviour so that they do not turn to criminal behaviour late in life.

  On the other hand, this evidence could be misused; could the fact that an individual has the amygdala of a criminal be used as evidence against them in court?
• Another ethical issue, is if criminal behaviour is caused by biological factors, can we hold people responsible for their actions? 

  Should be punish criminals if their behaviour was caused by physiological forces beyond their control?
• Another ethical issue is that all of these theories place the blame for offending inside the offender.

  It could be argued that by doing this it absolves society and the government of any responsibility. 

  It has been argued that the main reason for crime is social inequality and poverty. 

  By placing the blame within the criminal, it is ignoring the real reasons for crime.